[cornelious2]

As I state in my guide, I take no responsibility if you break the phone, but from what I read, pretty much every bad thing you can do is now reversible.

Basically you are correct about the customs roms, basically these roms are images of the windows mobile operating system with various custom drivers, programs, registry entries, etc. you can adjust a thing called the page pool when changing your roms, which would affect the free rom, but if you install a good rom (like no2Chems) you shouldn't need to bother with that untill you really get comfortable with the process and are trying to squeeze out ounces of performance.

If you are on sprint, its REALLY easy to get back to stock as on HTC's website you just download the exe, plug in your phone and run the exe. if your on verizon, its just a matter of downloading the stock rom from the ftp someware on here.

basically the more stuff you want running on your phone, the less free memory you will have free, you have to find the proper balance that works for you. If you have any issues going through my guide, just post there and I will do my best to help you or find someone that can. but since you are on sprint, it should be a really simple process as you don't need to worry if the sprint customizations run and whatnot.